Enthalpies of formation of 2-methyl-2-ethoxypropane and 2-ethyl-2-ethoxypropane from equilibrium measurements

The equilibria for the synthesis of C 2H 5OC(CH 3) 3(A) and C 2H 5OC(CH 3) 2(C 2H 5) (B) from C 2H 5OH (C) and CH 2:C(CH 3) 2(D) or CH 3CH:C(CH 3) 2(E) in the liquid phase were investigated at temperatures from 313 K to 412 K. On the basis of experimental equilibrium constants found for n(C)/ n(D) or n(C)/ n(E) ≥ 4, the following values were obtained for Δ r H m°/(kJ·mol −1) and Δ r S m°/(J·K −1·mol −1): (C + D = A),−(35.45 ± 1.94) and −(82.37 ± 5.99); (C + A = B), −(34.13 ± 0.81) and −(87.82 ± 2.18). The following values of Δ f H m°(298.15 K)/(kJ·mol −1) have been derived: C 2H 5OC(CH 3) 3(1),−(350.8 ± 2.6); C 2H 5OC(CH 3) 2(C 2H 5)(1), −(379.8 ± 1.4).